The present invention relates to electrical servo actuators and particularly those of the type powered by a small relatively high RPM, low voltage motor such, as for example, would be utilized for on-board motor vehicle control functions.
It has become increasingly attractive from a cost and control resolution standpoint to employ electrically operated servo actuators for controls in a motor vehicle such as those used for actuating an air flow valve either for engine air flow control or for controlling flow in the vehicle climate control system. Actuators of this type typically operate with a sub-fractional horsepower direct current motor operating at high RPM with low torque with the motor driving the device to be actuated through a speed reduction unit such as a gear train.
Heretofore, such servo actuators employed in motor vehicle applications have required relatively costly and complicated brackets and fasteners for attaching the motor to the servo actuator housing and for connecting the motor electrical terminals to the vehicle wiring harness. In addition, it has been found difficult to assemble the servo actuator and to mount the motor and make the electrical connections in high volume mass production for passenger car and light truck vehicles.
During the assembly process, loose wires are difficult to contain and prevent damage. This new device provides unique protection which prevents misrouting, cutting and scraping, shorting and pinching of the loose wires which improves robustness. This design also protects against solder shorts via the flange around the terminals to shield solder bridges from reaching the motor housing.
Upon the load device, such as an air valve, reaching its limit of travel or hitting internal stops provided for the position of the valve member at a fully open or fully closed position, the motor, operating at a relatively high RPM on the order of 3000 RPM is subjected to a significant sudden inertial reaction torque. Therefore, it has been found necessary to provide for the motor mounts to absorb the reaction torque and has thus complicated the mounting of the motor and required costly fasteners.
Thus, it has long been desired to provide a motorized servo actuator, particularly one for low voltage operation, which is relatively low in manufacturing cost, easy to assembly and provides for absorption of sudden inertial reaction torque against the motor mounts encountered upon the servo actuator reaching its limit position with the motor turning at a relatively high RPM.